Characterization of a new class of nuclear localization signals

一类新型核定位信号的表征

• 批准号: RGPIN-2019-05222
• 负责人: Kapus, Andras
• 金额: $ 4.23万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=715422
• 关键词: Characterization; new; class; nuclear; localization

The nucleus of animal and human cells is a vitally important cellular organelle that contains all our genes and the machinery that regulates them. Controlled gene expression, i.e. the regulated transfer of information from our genetic blueprint, the DNA, to the molecular “assembly lines” that build up our proteins is indispensable for all cellular function, including, growth, proliferation, metabolism and movement. Information transfer between the nucleus and other parts of the cells requires the continuous and subtly controlled entry and exit of proteins into and out of the nucleus. Of the approx. 20,000 different proteins of the human body, almost one third (>6000) has the capacity to localize to the nucleus. Entry and exit also called nuclear import and export occurs via specialized gates, the nuclear pore (NP). This large protein complex acts both as a guide and a barrier, thereby controlling the shuttling of proteins across the nuclear membrane. Understanding this traffic, which is essential for all normal cell functions, is a fundamentally important aspect of cell biology. How does the NP recognize which molecules are to be transported (i.e. which is the “cargo”) and which direction they should go (import or export)? Cargo molecules contain “molecular postal codes” or so called nuclear localization and nuclear export signals (NLS and NES). These molecular segments interact with elements of the transport machinery. Surprisingly, however, such postal codes are unknown in 60% of shuttling proteins. During our previous work on the regulation of a growth-promoting protein, we identified a new sequence, which has the capacity to mediate nuclear import. This is a unique postal code, which vastly differs from all the known NLS. We also discovered that import of this new signal is regulated by mechanical factors, acting via the cell's skeleton. Importantly, we also found similar molecular signatures (variant of the sequence) in a whole set of other, unrelated proteins, which are all known to control gene expression. These proteins play key role in variety of functions, including lipid metabolism, cell growth and immune defense. However we do not know if these variants of the discovered sequence can bring about import and affect protein function. Based on our results, we hypothesize that this molecular signature represents a new class of NLS. The objective of our research program is to characterize this NLS. We wish to identify the critical features necessary for its efficient nuclear entry, the mechanism and regulation of its import and its role in the localization and function of the proteins that contain it. We have started building a whole new molecular toolkit, which will allow us to monitor the nuclear traffic and function of the new NLS. These studies therefore have the capacity to unravel an entirely new class of nuclear localization signals, major step in understanding nuclear traffic, a fundamental process in all vital functions.

动物和人类细胞的细胞核是极其重要的细胞器，包含我们所有的基因和调节它们的机制。受控的基因表达，即信息从我们的基因蓝图 DNA 到构建蛋白质的分子“装配线”的受控转移，对于所有细胞功能（包括生长、增殖、代谢和运动）都是不可或缺的。细胞核和细胞其他部分之间的信息传递需要蛋白质连续且微妙地控制进出细胞核。 的约。人体 20,000 种不同的蛋白质中，几乎三分之一 (>6000) 具有定位于细胞核的能力。进入和退出也称为核输入和输出，通过专门的门（核孔（NP））进行。这种大型蛋白质复合物既充当引导者又充当屏障，从而控制蛋白质穿过核膜的穿梭。了解这种交通对于所有正常细胞功能至关重要，是细胞生物学的一个基本重要方面。 NP 如何识别哪些分子要被运输（即哪个是“货物”）以及它们应该朝哪个方向（进口或出口）？货物分子包含“分子邮政编码”或所谓的核定位和核输出信号（NLS 和 NES）。这些分子片段与运输机械的元件相互作用。然而，令人惊讶的是，60% 的穿梭蛋白中的邮政编码是未知的。在我们之前对生长促进蛋白的调控的研究中，我们发现了一个新的序列，它具有介导核输入的能力。这是一个独特的邮政编码，与所有已知的 NLS 有很大不同。我们还发现，这种新信号的输入受到机械因素的调节，通过细胞骨架发挥作用。 重要的是，我们还在一整套其他不相关的蛋白质中发现了类似的分子特征（序列的变体），这些蛋白质都已知控制基因表达。这些蛋白质在多种功能中发挥着关键作用，包括脂质代谢、细胞生长和免疫防御。然而，我们不知道所发现序列的这些变体是否会带来输入并影响蛋白质功能。根据我们的结果，我们假设这种分子特征代表了一类新的 NLS。我们研究计划的目标是描述该 NLS 的特征。我们希望确定其有效进入核所需的关键特征、其输入的机制和调节以及其在包含它的蛋白质的定位和功能中的作用。我们已经开始构建一个全新的分子工具包，这将使我们能够监测新 NLS 的核流量和功能。因此，这些研究有能力揭示一类全新的核定位信号，这是理解核交通的重要一步，核交通是所有重要功能的基本过程。